Defining 2D array inside class of Perl - arrays

Question

I am new to Perl and I am trying to define a 2D array as an attribute of my class in Perl. I define my class as follows,
sub new{
my $class = shift;
my $self = {};
my #board = [];
for (my $i = 0; $i < 8; $i++){
for(my $j = 0; $j < 8; $j++){
$board[$i][$j] = '.';
}
}
$self->{board} = #board;
bless($self, $class);
return $self;
}
But later on when I try to access the board field like this
$self->{board}[$i][$j] = ' ';
I got an error saying
Can't use string ("8") as an ARRAY ref while "strict refs" in use
Can anyone tell me what is the correct way of doing this? I do not want to just delete use strict.

Answer 1

I changed your code to what I'm sure was your intention,
see the lines changed and comment # not
sub new{
my $class = shift;
my $self = {};
my #board = (); # not []
for (my $i = 0; $i < 8; $i++){
for(my $j = 0; $j < 8; $j++){
$board[$i][$j] = '.';
}
}
$self->{board} = \#board; # not #board
bless($self, $class);
return $self;
}
or
sub new{
my $class = shift;
my $self = {};
my $board = []; # not #board
for (my $i = 0; $i < 8; $i++){
for(my $j = 0; $j < 8; $j++){
$board->[$i][$j] = '.';
}
}
$self->{board} = $board; # not #board
bless($self, $class);
return $self;
}
about your my #board=[]; is the same as =([],); assign a list (that perl calls ARRAY) whose first element is a reference to an ARRAY to #board, but this is neither what make your code fail because you overwrite this empty array reference allocation and assignment to position zero.
The #board is a list not a reference to it as $self->{board} expect

Answer 2

You need to place a reference to array inside your $self hash. Right now you're placing a value of array in scalar context - which is its length 8. Of course you can't later use this as a reference to anything.
$self->{board} = \#board;

Answer 3

Others have given you explanations of what the problem is with your constructor. I'll add, that you can simplify it a bit by omitting the $board variable and using C-style loops.
sub new {
my $class = shift;
my $self = {};
$self->{board} = [];
for my $i (1 .. 8) {
for my $j (1 .. 8) {
$self->{board}[$i][$j] = '.';
}
}
return bless $self, $class;
}
I'd also add the following three methods which make it easier to set and get the elements of the board:
sub board {
my $self = shift;
return $self->{board};
}
sub set_board_element {
my $self = shift;
my ($i, $j, $val) = #_;
$self->board->[$i][$j] = $val;
}
sub get_board_element {
my $self = shift;
my ($i, $j) = #_;
return $self->board->[$i][$j];
}
Have you considered using Moose to write your class? It will make your life easier. In particular, Array traits seem like a good fit for your problem.